Hafler xl-280 mods

[Audionirvana]

I've recently converted my home thetare setup from a HT receiver (Sony DA-3ES) to driving my 6.2 system with Hafler XL-280's on 4.2 channels (all except rear/ch sides).
I'd love to hear from xl-280 users the mods they liked the best.
I realize here are many Hafler owners out there (I've scoured this forum's Hafler topics) but I'd really like to hear from the xl-280 owners especially, as it incorporates many of the mods that were recommended for earlier models.
I am considering replacing the main boards' caps with 100uf/100v Black Gates.
Has anyone upped the PS capacitance or installed a better toroid power supply and how did they sound?
All comments appreciated.

[gp4Jesus]

hey I'ma XL 280 fan too.

Using 4 in HT too!! 3 for my LCR ina bi-amp config, the 4th full range. A different amp for my sub

It's true the 280 contains some "upgrades" that some in the DH200/220 crowd do to their amps. Still you may want to take a look at the thread below

http://www.diyaudio.com/forums/solid...-new-post.html


I realize 800+ posts are a lot to sift through. You will find there several people that will give you good sound advice. I have yet to make time to do anything except enjoy my system as-is. And I do enjoy it a great deal!

cheers tony

[HaflerFreak]

I own 2 XL280's, and honestly, don't know what to tell you. Each and everything I ever did to my amps made them sound worse.
I presume David Hafler cast a spell on each amp
OR
I have often thought that the cap technology was lightyears ahead of todays tech in the '80s.
The only thing I changed on my amps was the (old) caps, and, for me,
it destroyed the perfect 3D soundstage the amps shipped with.

After 'ruining' my XL280's, I started replacing resistors with RN60D's, experimented with modern versions of VAS transistors (2N5551/2N5401)
and... whatever. They're gone. Forever my reference in memory alone.

Good luck.

[gp4Jesus]

couldn't u just reverse the changes?

[HaflerFreak]

To a degree, I tried to do just that, but as a headstrong newbie I threw out the old caps. It certainly taught me a lesson and whenever I do something similar now, I save and mark parts for re-insertion if need be.

One note, I first changed the 100V 100uF rail caps with XICON high-temp caps. That may have sounded good. I recall it sounded very impressive so, of course, rather than enjoy it, I immediately delved back into the amp and replaced the 6.3V 1000uF feedback cap. That pretty much 'killed' the sound of the amp, and that cap turned out to be totally unreplaceable as it was a large can Nichicon BP.

Currently, I plan on replacing the current 16V 1000uF BP with a Nichicon Muse BP if I ever get around to working on it again. The amp is perfectly functional, so I am focusing on my newest project, my first DIY amp ever - an F5.

I cannot wait to compare the F5 to my Hafler memories, because it is JFET/MOSFET like the Haffie, the JFETs can be the same in both amps, but, the exciting part, the F5 has NO caps in the signal path.

[gp4Jesus]

Two items:

1. Looking for power supply improvements or upgrade ideas other than those on TnT-audio.com

2. On the XL-280 schematic I noticed 2 types of grounds.
(Pg 17 of the .pdf)
http://www.hafler.com/techsupport/pd...80_amp_man.pdf

One looks like a bent pitch fork (chassis ground?) The other, an inverted pyramid.

What concerns me is the 100nF caps that appear to rely on a chassis ground* connected to the final's PS rails near the MOSFETs.
* grounded through the heat sinks attached to case w/sheet metal screws.

Is it worth it to improve it? Can I run a connection to where C20 & C21 are grounded? Or where the RCAs have a way-better chassis ground?

Thanks tony